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A <br /> W <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> Steven T.Butler,Chair <br /> Grav Davis <br /> Vinston H.Hickos <br /> Secrcian•jor Sacramento Main Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/—rwgcb5 <br /> Protection 3443 Routicr Road,Suitc A.Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAx(916)255-3015 <br /> TO: Gordon L. Boggs FROM: Marty Hartzell <br /> UST Program Manager Associate Engineering Geologist <br /> DATE: 7 February 2000 SIGNATURE: <br /> SUBJECT: NONCONCURRENCE WITH SAN JOAQUIN COUNTY'S NO FURTHER <br /> ACTION REQUIRED DETERMINATION, <br /> TRACY COLD STORAGE, 24500 MACARTHUR ROAD, TRACY <br /> I reviewed the 24 December 1999 Case Closure Summary for Tracy Cold Storage submitted by San <br /> Joaquin County Environmental Health Division (County), and the 7 September 1999 Quarterly Report <br /> Groundwater Sampling June 15 and 22, 1999 and Case Closure Request with addendum prepared by <br /> American Geological Services, Incorporated (AGS). <br /> One UST was removed from the subject site in the 1970's. No information concerning soil or <br /> groundwater contamination was provided, however it was reported that the tank was removed because it <br /> was known to be leaking. Figure 1 presents a site map from AGS's Case Closure Request addendum. <br /> Multiple borings were completed, and a total of 9 monitoring wells were installed. Groundwater <br /> monitoring was conducted quarterly from June 1995 to June 1999. Results from June 1999 quarterly <br /> monitoring show TPHg at 3,800 µg/1 and benzene at 150 µg/1 at monitoring well MNNI-IA located near <br /> the former UST, and TPHg at 400 µg/1 and benzene at 5.1 µg/1 at MW-6 located 100 feet downgradient <br /> of the former UST. MtBE was analyzed at six monitoring wells in June 1996, October 1997, and <br /> December 1997, and was less than 1.0 µg/1 for all wells sampled. Lead was analyzed in twenty soil <br /> samples, and the maximum concentration was identified at 48 mg/kg. <br /> Excavation of impacted soils was completed in July and August 1998. ApnrR'`��ely Compound cubic <br /> was yards <br /> of soil was removed and aerated on-site. Following the excavation, Oxy, P <br /> added to the backfill materials to aid passive in-situ bioremediation. Since the over excavation activities <br /> were completed,TPHg and BTEX concentrations have decreased significantly at monitoring well MW_ <br /> lA located near the former UST. <br /> Two on-site domestic water supply wells are downgradient and within 100 feet of the former UST area. <br /> Tracy Cold Storage operates both wells The t below w well groundsurface,ed as and has a 50-foot sanitary seal constructed Well"was Th <br /> in 1984, is screened from 120 to 150 fee gr <br /> older well designated as the "South Well" is approximately 80 feet downgradient of the former UST, and <br /> in Jun <br /> well construction information is not available.The Southth wells were Wellmay not he sampled anitary seal9gand ou d act as BTEX constituents were not detected. <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />